1. Technical Field
The present invention relates to a method for mass-producing DLC films and an apparatus for mass-producing DLC films, and more specifically to a method and an apparatus for mass-producing DLC films on a plurality of plate-shaped substrates. DLC stands for diamond-like carbon.
2. Description of the Related Art
A DLC film, whose crystal structure is amorphous, is a material used in various technical fields because a DLC film has not only high hardness but also excellent mechanical properties such as wear resistance and low friction. Plasma CVD is known as a method for producing such a DLC film on a substrate. In this method, a DLC film is produced on a substrate by disposing a placement electrode on which the substrate is placed and a counter electrode facing the substrate in a chamber such that they have a certain interval and by applying a negative pulse voltage to the counter electrode in a carbon source gas atmosphere to generate plasma. DLC films can be produced on a plurality of substrates by this method. In this case, however, the counter electrode is required for each of the substrates, which results in upsizing of an apparatus.
In contrast, Patent Document 1 discloses a method for producing DLC films on a plurality of substrates without disposing counter electrodes. In this method, DLC films are produced on a plurality of plate-shaped substrates by holding the plurality of plate-shaped substrates stacked in a vertical direction in a chamber connected to ground such that the interval between the adjacent plate-shaped substrates in parallel and in a vertical direction is in a range of 2 to 30 mm, setting the internal pressure of the chamber in a range of 13 to 1330 Pa, injecting a carbon source gas from a plurality of nozzles to the chamber, and applying a negative voltage to each of the plate-shaped substrates to generate plasma. This method does not require a counter electrode, and thus an apparatus can be downsized. Furthermore, a sheath width can be narrowed by setting the internal pressure of the chamber in a range of 13 to 1330 Pa, and the interval between the plate-shaped substrates can be narrowed in accordance with the sheath width, and thus an apparatus can be further downsized    Patent Document 1: JP 2004-263292 A